EP0799272B1 - Acetylation of lignocellulosic fibres - Google Patents

Acetylation of lignocellulosic fibres Download PDF

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Publication number
EP0799272B1
EP0799272B1 EP95942338A EP95942338A EP0799272B1 EP 0799272 B1 EP0799272 B1 EP 0799272B1 EP 95942338 A EP95942338 A EP 95942338A EP 95942338 A EP95942338 A EP 95942338A EP 0799272 B1 EP0799272 B1 EP 0799272B1
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EP
European Patent Office
Prior art keywords
lfs
process according
acetylated
acetylating agent
acetylation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP95942338A
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German (de)
English (en)
French (fr)
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EP0799272A1 (en
Inventor
Helen Louise Nelson
David Ian Richards
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
A-Cell Acetyl Cellulosics AB
Original Assignee
A-Cell Acetyl Cellulosics AB
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Publication of EP0799272A1 publication Critical patent/EP0799272A1/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H8/00—Macromolecular compounds derived from lignocellulosic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B3/00—Preparation of cellulose esters of organic acids
    • C08B3/06—Cellulose acetate, e.g. mono-acetate, di-acetate or tri-acetate

Definitions

  • the present invention relates to a process for the production of acetylated lignocellulosic fibres (LF) wherein the lignocellulosic fibre is treated with acetic anhydride.
  • LF acetylated lignocellulosic fibres
  • lignocellulosic fibre is meant here and throughout the specification a material in any shape or form such as e.g. shreds, fibres, splinters and shives, and which is derivable from a source comprising wood, sisal, jute, coconut and/or other plant material and which has optionally been subjected to a pre-treatment with a non-acetylating catalyst, such as an acetate, e.g. sodium acetate or alkaline salt of an alkali metal in order to improve subsequent acetylation thereof.
  • a non-acetylating catalyst such as an acetate, e.g. sodium acetate or alkaline salt of an alkali metal in order to improve subsequent acetylation thereof.
  • LF non-acetylating catalyst
  • the first step comprises treating LFs with acetic acid/acetic anhydride at a temperature of 70-140°C and the second step comprises treating the reaction mixture from step 1 with a superheated chemical vapour of acetic acid and/or acetic anhydride at a temperature of 140-220°C and a pressure of 100-150 kPa.
  • the LFs may optionally be purified by hydrolysis.
  • One object of the present invention is therefore to provide an easier and quicker process for acetylation of LFs while maintaining the necessary degree of acetylation.
  • the present invention is a process for the acetylation of lignocellulosic fibres comprising bringing the LF into contact with a superheated acetylating agent comprising at least 20 % w/w acetic anhydride at a temperature above 140°C for a duration of at least 1.5 minutes so as to substantially acetylate the LF to achieve a weight gain of at least 2%.
  • the superheated acetylating agent used for this purpose has at least 20% w/w, preferably above 50% w/w of acetic anhydride.
  • the superheated acetylating agent suitably comprises 50-100% by weight, preferably 70-95% by weight of acetic anhydride.
  • the superheated acetylating agent is at a temperature above 140°C, suitably from 140-220°C, preferably from 160-195°C and the acetylation reactor is suitably operated at a pressure of 100-150 kPa.
  • the acetylation reactor Prior to commencement of acetylation, the acetylation reactor is suitably rendered gas-tight e.g. by using e.g. a plug screw or a rotary valve, at the point of entry into the reactor so as to minimise ingress of air into the acetylation reactor or egress of acetic anhydride out of this reactor.
  • the superheated acetylating agent is used to start-up the process.
  • the duration of this acetylation is relatively long and is usually of the order of at least 1.5 minutes, suitably at least 5 minutes, preferably up to about 10 minutes.
  • the LF to be acetylated may be optionally treated with a liquid acetylating agent, which may be hot or cold, for a very short period of e.g. less than a minute prior to being brought into contact with the superheated vapours of the acetylating agent.
  • a liquid acetylating agent which may be hot or cold, for a very short period of e.g. less than a minute prior to being brought into contact with the superheated vapours of the acetylating agent.
  • This liquid treatment step which is much shorter than the step involving the treatment with vapours of the superheated acetylating agent, would appear to enable rapid acetylation during the actual acetylation step according to the invention.
  • This is preferably achieved by spraying liquid and/or a mist comprising acetic anhydrides onto the fibres passing through this stage without immersing such fibres in a liquid thereby achieving intimate contact between the anhydride and the fibres without using an excess of the anhydride.
  • the present invention is substantially different from prior art processes in which the step involving contact with a liquid acetylating medium is considerably longer and thereby prolongs the whole of the acetylation process.
  • This method also minimises the stages where large and bulk quantities of liquid acetylating agents are handled or processed through the reaction stages.
  • This pre-treatment stage can be carried out in a closed system suitably operated under slightly reduced pressure in relation to atmospheric pressure in order to avoid inadvertent egress of acetic anhydride from the system.
  • a feature of the present invention is that the treatment of the LF with the superheated acetylating agent not only achieves the bulk of the acetylation of the fibres but also strips the acetylated LF of all excess acetylating agent or acetic acid such that the total amount of these remaining in their free occluded, adsorbed or absorbed form in the acetylated LF - but not chemically bound form - is less than 5% W/W of the acetylated LF.
  • the precise duration of the acetylation reaction of the LF in the reactor will be determined by the degree of acetylation desired and the nature and amount of the acetylatable material present in the LF.
  • the degree of acetylation is suitably such that the acetylated LF achieves a weight gain of at least 2%, preferably at least 5% and more preferably from 5-30% by weight.
  • the stripped, acetylated LF product emerging from the reactor can be further processed in a hydrolysis chamber in order to remove or at least minimise the odour of the chemicals in the acetylated LF.
  • the stripped product which is usually at an elevated temperature of about 130-160°C may be dispersed and entrained in a current of steam optionally with one or more other entraining gases. It is preferable to use superheated steam and in this instance, any residual unreacted acetic anhydride remaining adsorbed or occluded in the acetylated LF is hydrolysed to acetic acid and removed overhead as a mixture of steam and acetic acid from the hydrolysis chamber.
  • This mixed vapour may be recirculated to the superheated steam being introduced into the hydrolysis chamber.
  • the effect of this step is that it significantly reduces the acetic acid or anhydride odour of the treated LF product by removing substantially all of the unreacted acetic anhydride therefrom and also most of the acetic acid therein.
  • the amount of acetic acid left behind in the acetylated product is suitably less than 0.5% w/w.
  • the acetylated LF after removal of any residual unreacted anhydride using superheated steam and emerging from the hydrolysis chamber, is usually at a temperature of about 150°C.
  • This product can be sent either directly to an adjoining plant where said product can be formed into the desired shapes e.g. boards, or, can be subjected to a further humidifying and a cooling step in order to bag the material for storage and distribution. This may be achieved by passing a current of steam and air over the treated LF emerging from the hydrolysis chamber so as to cool the treated LF to about 40°C and to humidify it.
  • the process of the present invention is particularly suitable for acetylating fibres, especially of wood fibres, which may vary in dimensions e.g. from 0.03 mm to 4 mm in length. Furthermore, the process of the present invention can be operated batchwise or continuously, an option not available in the conventional processes used hitherto.
  • Raw lignocellulosic fibre is fed into a hopper (1) and via a star feeder device (in order to maintain the superheated acetylating loop gas tight) into a narrow chamber (2), purged initially with nitrogen to displace any air or oxygen therein, where the LF is sprayed with a mist of acetic anhydride at several points along its passage through the chamber (2).
  • the LF is pre-treated with acetic anhydride by bringing the LF into intimate contact with the anhydride and thereby moistening it with acetic anhydride.
  • This chamber (2) is maintained at a pressure slightly below atmospheric to prevent back flow of the acetic anhydride.
  • the LF moistened with acetic anhydride and emergent from the chamber (2) is then fed to the acetylation reactor (3), also previously purged with nitrogen to exclude any air or oxygen therein, where it is brought into contact with superheated vapour of an acetylating agent containing neat acetic anhydride introduced at (4) or optionally containing some acetic acid from recycled streams at about 190°C.
  • the pre-treated LF is entrained in the superheated vapour stream fed to the base of (3) and has a residence time in (3) of at least 1.5 minutes in order to achieve the degree of acetylation desired.
  • Reactor (3) not only fulfils the function of acetylating the LF but is also a steam jacketed circulation stripper where the chemicals adsorbed or occluded in the acetylated LF are evaporated.
  • the overheads from the reactor (3) entraining the acetylated LF are fed into a circulation cyclone (5) where hot, acetylated LF is recovered from the base thereof and is fed through a rotary valve (not shown) into line (6).
  • the overheads from the cyclone (5) is recirculated back to reactor (3) except for a bleed (not shown) to processing and recovering of acetic acid formed as a by-product in the acetylation step, and admixed with acetic anhydride being superheated in order to restore the desired composition of the acetylation agent.
  • the acetylated LF is dispersed in and entrained by a mixture of superheated steam and some acetic acid vapour (from partly recycled streams) and is then fed into a steam stripper (7).
  • any residual, unreacted acetic anhydride in the acetylated LF is hydrolysed to acetic acid and the acetic acid is stripped out.
  • the overheads from the steam stripper (7) which are at a temperature of about 150°C, are fed into a steam stripper cyclone (8) where the acetylated LF is separated from the vapours and recovered from the base thereof whereas the acidic vapours are recovered overhead therefrom to be processed and recycled.
  • the acetylated LF substantially free of all free acids and anhydrides (and hence the odours of these components) recovered from the base of (8) can either be sent to an adjacent board manufacturing facility (not shown) directly or can be humidified and cooled for the purposes or bagging and storage (not shown).

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Biochemistry (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Compounds Of Unknown Constitution (AREA)
EP95942338A 1994-12-19 1995-12-18 Acetylation of lignocellulosic fibres Expired - Lifetime EP0799272B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9425765 1994-12-19
GBGB9425765.6A GB9425765D0 (en) 1994-12-19 1994-12-19 Acetylation of lignocellulosic fibres
PCT/SE1995/001531 WO1996019526A1 (en) 1994-12-19 1995-12-18 Acetylation of lignocellulosic fibres

Publications (2)

Publication Number Publication Date
EP0799272A1 EP0799272A1 (en) 1997-10-08
EP0799272B1 true EP0799272B1 (en) 2002-03-20

Family

ID=10766265

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95942338A Expired - Lifetime EP0799272B1 (en) 1994-12-19 1995-12-18 Acetylation of lignocellulosic fibres

Country Status (9)

Country Link
US (1) US5821359A (da)
EP (1) EP0799272B1 (da)
AU (1) AU693631B2 (da)
CA (1) CA2208080C (da)
DE (1) DE69525967T2 (da)
DK (1) DK0799272T3 (da)
GB (1) GB9425765D0 (da)
NZ (1) NZ298164A (da)
WO (1) WO1996019526A1 (da)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9322187D0 (en) * 1993-10-28 1993-12-15 Bp Chem Int Ltd Acetylation of lignocellulosic materials
US20100331531A1 (en) * 2009-06-25 2010-12-30 Eastman Chemical Company Methods for esterifying lignocellulosic material
US8906466B2 (en) * 2009-06-25 2014-12-09 Eastman Chemical Company Esterified lignocellulosic materials and methods for making them
EP2289980A1 (en) 2009-07-30 2011-03-02 Danish Plant Fibre Technologies Holding A/S A process and apparatus for modification of lignocellulosic materials and products of modified lignocellulosic materials obtained by the process
US9091022B2 (en) * 2011-01-10 2015-07-28 Danish Plant Fibre Technologies Holding A/S Process and apparatus for modification of lignocellulosic materials and products of modified lignocellulosic materials obtained by the process
CO6910042A1 (es) 2011-09-28 2014-03-31 Titan Wood Ltd Paneles de fibras de densidad media
EP2623281A1 (en) * 2012-01-31 2013-08-07 Titan Wood Limited Acetylated wood
PE20200032A1 (es) * 2012-03-21 2020-01-09 Titan Wood Ltd Metodo para la modificacion de madera
BR112014029241B1 (pt) * 2012-05-22 2021-01-05 Titan Wood Limited sistema de reator e processo para a acetilação de materiais lignocelulósicos e uso de um sistema de reator para conduzir um processo para a acetilação de materiais lignocelulósicos
EP3004217A1 (en) 2013-06-03 2016-04-13 Chemconserve B.V. Modified wood fibres for manufacture in composites
CN107000243B (zh) * 2014-07-16 2019-11-08 特里科亚科技有限公司 使木材乙酰化的方法
US11338468B2 (en) 2015-04-13 2022-05-24 Tricoya Technologies Ltd. Method for continuous acetylation of wood elements
US20180079104A1 (en) * 2015-04-13 2018-03-22 Tricoya Technologies Ltd Method for continuous acetylation of wood elements
KR102482912B1 (ko) * 2016-06-23 2022-12-29 트리코야 테크놀러지스 엘티디 아세틸화된 목재 요소 냉각
EP3741793A1 (de) 2019-05-22 2020-11-25 Basf Se Faserformteile

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3403145A (en) * 1962-07-10 1968-09-24 Rayonier Inc Acetylation of cellulose
GB2271570A (en) * 1992-10-15 1994-04-20 David George Rogers Treating lignocellusosic material with acetic anhydride
JPH079411A (ja) * 1993-06-25 1995-01-13 Sumitomo Chem Eng Kk セルロース含有材のアセチル化法および改質木材の製造方法
GB9322187D0 (en) * 1993-10-28 1993-12-15 Bp Chem Int Ltd Acetylation of lignocellulosic materials

Also Published As

Publication number Publication date
DE69525967T2 (de) 2002-11-28
EP0799272A1 (en) 1997-10-08
CA2208080A1 (en) 1996-06-27
DK0799272T3 (da) 2002-06-03
AU4358896A (en) 1996-07-10
DE69525967D1 (de) 2002-04-25
AU693631B2 (en) 1998-07-02
NZ298164A (en) 1998-05-27
WO1996019526A1 (en) 1996-06-27
CA2208080C (en) 2006-11-28
US5821359A (en) 1998-10-13
GB9425765D0 (en) 1995-02-22

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